Reduction of excessive heavy metals accumulation in drinking water with natural zeolites

Abstract

This paper reports on the study of heavy metal removal from groundwater intended for human consumption using natural aluminosilicates of the zeolite group. The natural zeolite material has been extracted from the Sokirnica deposit located in the Zakarpattia Region in Ukraine. The central focus of this study was the course of the heavy metal adsorption process itself, in which natural zeolites were applied for the removal of Cr, Cd, Ni and Pb ions from aqueous solutions in the presence of large amounts of Ca and Mg ions, competing for ion exchange sites. The capacity of zeolite as an adsorbent was assessed with the use of adsorption isotherms prepared for the heavy metals under tests, whereas the mathematical description of the process was provided by Freundlich and Langmuir isotherm equations. The results from the analysis confirm the high efficiency, and thus the applicability, of zeolite deposits in water filtration. The effective Cr, Cd, Ni and Pb removal rate from groundwater intended for human consumption was confirmed even when the content of these metals in water was exceeded by a factor of 10, compared to the permissible limits provided in legal regulations.